Wafers of semiconductor material such as silicon and gallium-arsenide with integrated circuits formed thereon have a relatively large diameter. In the production of integrated circuits (IC), such a wafer is adhered to a pressure sensitive adhesive tape, sometimes called a dicing tape, and diced into IC chips. The IC chips (die or dice) are then removed from the dicing tape, an adhesive is applied to the chip or to a substrate, the chip is placed on the substrate and the adhesive is cured to attach the die to the substrate.
Dicing tapes must provide strong adhesion to a semiconductor wafer during the step of dicing the wafer into individual chips. However, the dicing tape also should subsequently provide a sufficiently low adhesion to the die to allow the individual chips to be removed from the tape quickly, cleanly, and easily. That is, it is useful for the dicing tape to have a reduced adhesion when the chip is removed, and there should be no residue from the dicing tape on the chip. Therefore dicing tapes have been prepared that have a balance of adhesion to the wafer to adhere strongly during the dicing step, but the tape also releases from the individual chips without leaving a residue on the chip when the chip is removed from the tape. Some dicing tapes have been prepared which may be detackified upon exposure to ultraviolet light to improve the clean removal of individual chips. Without a balance of adhesion, it is difficult to carry out the steps of dicing the wafer and picking and placing the individual chips. If the adhesion of the dicing tape is not balanced and some adhesive remains on the individual chip when it is removed from the dicing tape, additional steps are required to remove the adhesive residue from the chip. These additional steps often include organic solvents.
After the dicing operation and chip singulation is complete, a second adhesive subsequently must be placed between the chip and the substrate to hold the chip securely in place on a substrate. The second adhesive, often referred to as a die attach adhesive, can be applied to the surface of a chip that is opposite the circuits or it may be applied directly to the substrate to which the chip will be bonded. Using a separate die attach adhesive requires additional steps and equipment to place the adhesive either on the chip or the substrate. Some separate die attach adhesives have been epoxy resins that can be cured once the chip has been placed on the substrate.